Having just discovered yet another device with battery damage, I thought I’d raise the subject of switching away from zinc-chloride and alkaline single use cells, to the newer style of low self discharge Nickel Metal Hydride rechargeable cells. They are sometimes called “ready to use” or “pre-charged” cells due to retaining a useful capacity even when stored before retail.

They won’t work in all equipment due to their slightly lower cell voltage (1.2V vs 1.5V), but do work in most stuff, and are much less prone to leakage.

The science of alkaline cell leakage may be down to the natural formation of gas bubbles during normal discharge. That results in a gradual increase in internal pressure that may eventually force the corrosive electrolyte out through the seal. That could be during normal use of a new battery, or it could be a long term thing when batteries have been left in a piece of equipment.

Rechargeable cells like NiMh batteries do generate gas internally during charge, but self catalyse it back to liquid electrolyte internally. It usually takes serious overcharging to make them vent.

For the last few years, very well-informed people have been able to tell if an alkaline battery is good or not simply by dropping them. When dropped from an inch or two above a hard surface, a good battery won’t bounce, and will sometimes land standing up. A dead battery, on the other hand, will bounce.

the reason dead alkaline batteries bounce is due to the electrolyte. [Lee] cut open a few AA cells and found the electrolyte in a good battery was a mushy mess of chemicals. In the dead battery, this same electrolyte hardened into a solid mass.

There are a number of resources scattered across the Internet that provide detailed breakdowns of common products, such as batteries, but we haven’t seen anything quite as impressive as this site.

This page is about flashlights, batteries, chargers and sometimes other stuff.
http://lygte-info.dk/

Can you determine the charge of an alkaline battery by simply dropping it and see how high it bounces?

The debate over which battery brands work best is almost as old as dry cells themselves, but one US city has learned that it’s definitely not a good idea to skimp when it comes to powering important municipal equipment.

the discount batteries that Detroit is using now don’t do the job as well as the name-brand alkaline cells the city used before budget cuts took effect.

As a result – according to the office of the emergency manager, whose thankless job it is to oversee the city’s ongoing fiscal crisis – on any given day, nearly half of Detroit’s parking meters aren’t working.

Dead meters mean Detroit loses more than just coins. Legally, the city can’t give parking tickets to cars parked at broken or nonfunctioning meters.

Consider that, the next time you’re shopping for batteries for your smoke alarm.

Information Article about 9 Volt Lithium Ion Rechargeable Batteries and Chargers
http://www.megabatteries.com/9_volt_li-ion_batteries_and_chargers.html

The power out of these 9 volt rechargeable batteries ranges between 400 – 600 mAh (milliampere-hours), and will power your 9 volt device(s) for longer periods of time (called run-time) than NiMh (Nickel Metal Hydride) chemistry batteries.

See the difference: 9 volt NiMh’s are rated from 250 -300 mAh, clearly making 9 volt Lithiums twice as strong with twice the power (run time)!

When sourcing these batteries, always be sure to buy from a trustworthy and reliable supplier. One who delivers proper technical information to you PRIOR to your purchase

Charging Lithium-ion
http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

Achieving the Most from Your Rechargeable Batteries
http://www.horizonbattery.com/ansmann-pro-audio-division/tips-for-successful-recharging

Anyone tried 9v lipo batteries?
http://www.eevblog.com/forum/reviews/anyone-tried-9v-lipo-batteries/10/?wap2

kaptain_zero:
I just got one of the 9V batteries from DX
I charged it up in my 9V Lithium/NiMH/Nicad charger and then used one of my iChargers to discharge and measure the capacity. Peak voltage after charge was just over 8.4V,

I ended up getting 484mAh total when the internal battery protection circuit kicked in at ~6.25V

So… if using these types of batteries, there are a few quirks one must be willing to accept.
1. Low voltage vs primary cells. Many devices will be quite happy to run on 6.x to 8.x, but not all.
2. If using the cell until it goes dead, be aware that it goes dead *suddenly* when the protection circuit kicks in.
3. Lithium Ion chemistry is not the best for little used devices. A fully charged Lithium cell will deteriorate faster than one that is partially charged
4. Compared to NiMH, LiIon has a shorter lifespan and does not store well.

5. LiIon with it’s low internal resistance can cause problems should the battery short out by contacting something conductive by accident, and this could result in a “vent with flames” event. I do not know if there is short circuit protection in the internal protection device. All that is mentioned on the battery is that one should not draw more than 0.5A in use.
6. Cell balance. This is an issue unless the internal circuit manages it. Unlike NiHM or Nicad where trickle charging is used to bring the cells into balance, trickle charging is unsafe with Lithium based cells.

For me, too many downsides to switch to this type of cell. Yes, the capacity is nice

NiHaoMike:
The rechargeable lithium batteries, if they’re for consumer use, should have overcurrent protection built in. However, older NiMH batteries have no protection whatsoever and will supply very large currents to short circuits. (Some newer ones have built in PTCs.)
Some devices use the very high current capability of NiMH AAs

How long should things last? I think it depends on what you are willing to tolerate.

While I used a dollar-per-day of ownership to target the replacement of my laptop, there are other targets. You may want to keep the equipment until the embedded battery no longer can support the run time expectations. I do appreciate the embedded battery strategy as long as the battery life meets my level of tolerance for truly portable operation. As a side note, I have an electric razor that has had the same battery for 8 years.

Battery degradation is a popular topic or complaint. Most portable users just accept the phenomena. They live with it by purchasing a replacement battery, if their battery is replaceable, or replace the entire device. A colleague of mine, Yevgen Barsukov, presented on this topic of battery degradation at this year’s International Battery Seminar and Exhibit.

Just knowing the kinetics of battery degradation can help determine actions that can reduce the rate of the phenomena. For example, temperature accelerates degradation and higher state charge further increases the reaction rate. So charging your device to full and then leaving it in your car in the summer, can take weeks off your battery’s life.

Battery degradation occurs in two areas: Coulomb losses and impedance increase. Coulomb losses are due to loss off active materials such as Lithium or cathode material. This loss is due to the material not being able to participate in energy cycling. Impedance increase reduces the rate capability of the battery, causing the battery to produce lower terminal voltages during discharge and slower recharge cycles.

Barsukov addressed Lithium plating as one component of capacity degradation. This component results in the loss of Coulomb capacity.

Figure 1 shows the results from Barsukov’s paper using multi-level charging compared to the traditional constant-current, constant-voltage charging (CCCV).

Although you may not be able to recover the degradation once it occurs, it seems that you can keep some of the components from happening. In doing so, the life of the portable equipment with embedded batteries can be extended. In the end, batteries do wear out. You replace them when they are removable, or replace them along with the entire portable device when they are not.